Seedmate. BIP39 calculator: Seedmate is an air-gapped, standalone BIP39 calculator

On July 31st, 2026, Coldcard reported that a firmware bug had weakened how some devices generated seed phrases leading to significant user losses. This is not the first time a wallet created weak seed phrases, and it won't be the last. I started developing an offline BIP39 calculator with this risk in mind, some months ago. Now I kind of have to launch it, given the circumstances. It can be used for seed generation using real world randomness: dice rolls, coin toss, poker cards, random word picks and a stopwatch. The random work pick being the most transparent and trust less method of them all. Additionally you can mix different randomness sources via XOR logic. Also it allows different strategies to store your seed redundantly and safely from prying eyes using XOR logic or Shamir Secret Sharing. Finally it provides obfuscation functions. Rather than storing a clear-text copy of your seed, you can apply reversible transformations to it. If someone finds your backup, they won't gain access to your funds unless they know the exact reverse logic.